This invention relates generally to an apparatus having an articulated boom to support an appliance. The invention also relates to a method of controllably supporting, positioning and restraining an appliance. More particularly, the invention relates to an articulated boom comprised of front and rear arms, each arm composed of a mechanical linkage which is biased by a combination of a hydraulic shock absorber and springs to support a load applied to the articulated boom, enabling smooth and controllable orientation of an appliance in a variety of positions.
Prior apparatus for supporting an appliance have employed friction clutches to control movement of the arms of the support apparatus (e.g., see U.S. Pat. No. 4,447,031). These friction clutches provide a positioning/locking feature in the support arms; however, these clutches wear with use, and are therefore susceptible to premature failure.
Another problem inherently associated with certain prior art devices (e.g., see U.S. Pat. No. 4,447,031) is the possibility of the devices causing injury as a consequence of failure of a lock mechanism used on these devices. The lock mechanism is used to secure the support arm in a compact position during installation and maintenance. With the lock mechanism in place, the springs of the biasing system are highly tensioned. If a user or installer inadvertently or improperly disengages the lock mechanism, serious bodily injury can result because the support arm will move quickly and violently.
An additional problem associated with prior art devices using springs alone in the biasing system is the breaking of a spring in the arm. If such a break occurs, the arm and appliance will quickly rise or fall depending upon which arm experiences the spring breakage.